DevTools: Cache the original content on UISourceCode

third_party/WebKit/Source/devtools/front_end/workspace/Workspace.js

Index: third_party/WebKit/Source/devtools/front_end/workspace/Workspace.js
diff --git a/third_party/WebKit/Source/devtools/front_end/workspace/Workspace.js b/third_party/WebKit/Source/devtools/front_end/workspace/Workspace.js
index 35c15398b42939bc7e0f796073a67642d08f6e26..c7c4d9405e32a6176e96735e6ba29da704cffc90 100644
--- a/third_party/WebKit/Source/devtools/front_end/workspace/Workspace.js
+++ b/third_party/WebKit/Source/devtools/front_end/workspace/Workspace.js
@@ -104,6 +104,12 @@ Workspace.Project.prototype = {
   requestFileContent(uiSourceCode, callback) {},
 
   /**
+   * @param {!Workspace.UISourceCode} uiSourceCode
+   * @return {!Promise<?string>}
+   */
+  requestOriginalFileContent(uiSourceCode) {},
+
+  /**
    * @return {boolean}
    */
   canSetFileContent() {},
@@ -111,7 +117,7 @@ Workspace.Project.prototype = {
   /**
    * @param {!Workspace.UISourceCode} uiSourceCode
    * @param {string} newContent
-   * @param {function(?string)} callback
+   * @param {function()} callback
    */
   setFileContent(uiSourceCode, newContent, callback) {},